Metal tube



June 1938- D. D. KNOWLES ET AL 2,121,600

METAL TUBE Filed Aug. 26, 1936 WITNESSES: INVENTORS Er'vgn E Lawry.

Dewey D. Knowles and Patented June 21, 1938 UNITED STATES PATENT OFFICE METAL TUBE vania Application August 26, 1936, Serial No. 97,972

6 Claims.

Our invention relates to electron discharge devices and especially to such devices having a casing substantially all metal.

It is an object of our invention to provide an electron discharge device having a container of substantially all metal and in which the means whereby the various parts are sealed together also serves to separate electrically the adjacent metal surfaces.

Another feature of our invention is a method whereby the insulating seal elements of the device are maintained under considerable more compression than those of the prior art.

Other objects of our invention and advantages thereof will be apparent from the following description of preferred embodiments and the accompanying drawing, in which:

Figure l is a view mainly in cross section of a device constructed in accordance with our invention,

Fig. 2 is a detail view partly in cross section and partly in elevation illustrating a modification of Fig. 1,

Fig. 3 is a top plan view of a modification of the walls of Fig. 1,

Fig. 4 is a sectional view taken along lines IV-EV of Fig. 3, and

Fig. 5 is a cross sectional View of a modification of Fi 1.

In constructing practically all metal tubes we prefer to form sections of metal in accordance with the number of electrodes or rather electrode leads to the device. In our preferred embodiment, We prefer to take several tubes of varying diameters, each of these tubes having a large diameter at one end and a reduced diameter at the other end. For example, the smallest diameter tube has a large end ID .and a small end II. The next size tube has a large end l2 and a small end E3. The next larger tube has a large end l4 and a smaller end l5. The largest tube has a large end I6 and a small end l1. Intermediate these large ends and small ends of these tubes are conical portions l8, I9, and 2|. The smaller tube has its smallest end closed at 22 and the largest tube also has its smaller end closed at 23.

While the metal of these tubes may be that of any suitable composition, we prefer to construct it of the composition of iron, nickel and cobalt described in the copending application of Howard Scott, Serial No. 376,291, filed July 5, 1929. We prefer to place on the outer conical section of l8 of the smaller tube vitreous material 24 such as glass and to seal the adjacent conical section l9 thereto. Likewise, the conical section l9 can be sealed to the adjacent conical section 20 by the vitreous material 25 and the vitreous material 26 can in turn seal the adjacent conical sections 20 and 2|.

At any step in the process, the cathode 30 may be supported from the inner head 22 of the small diameter tube and the small end 13 of the next larger size tube. -A grid 29 is also preferably extended across the open end of the next larger diameter tube l5.

A device is, accordingly, formed having a practically all metal casing with a cathode supported between two metal portions thereof, a grid supported by another portion and the outer metal casing adapted to act as an anode. Of course, the grid could be eliminated if only a two-electrode tube is desired, and additional metal tubes with insulation therebetween inserted if more electrodes such as the screen and space grids are desired. The connections may be made more conveniently by attaching directly to the portions of the large ends Ill, l2 and M of the tubes and at any portion iii of the outer tube.

The fluxing of the various vitreous surfaces together to form a vacuum tight seal may be accomplished by any desired method, but it is preferred to assemble the various parts in proper mechanical relation and to put the device under partial vacuum. The tubulation for evacuating the device may be attached to any suitable portion of the envelope. The conical portions may then be heated or indeed the Whole assembly be heated until the vitreous surfaces become softened or plastic and the atmospheric pressure acting on the outer surfaces will force the entire arrangement together until a solid seal is formed and the vitreous materials may then harden under pressure.

It will be noted that the arrangement of nesting the various conical sections and having the outer portions slightly superimposed upon the inner ones gives an extraordinary degree of me chanical strength inherent in the structure.

The assembly is made very economically and the shaping of the tubular portions gives any desired spacial and axial alignment of the component metallic portions of the tube.

If it is desirable for any reason to increase the normal distance between two or more of the conical surfaces or to prevent excessive flow of the vitreous seal material during the sealing process, a refractory ceramic insert or other suit able material may be added as disclosed in Fig. 2. In this figure, the adjacent conical walls 3| and 32 have the vitreous sealing material 33 there-between. In the upper and lower boundaries of this vitreous sealing material are the reiractory ceramic inserts l4 and designed to ilx accurately the separation between the wall sections II and 32 and also to prevent excessive flow therefrom oi the vitreous material 33 during the sealing process.

Ii desired, the metallic portions may be made up of two or more parts, each separated from the other by vitreous glass or enamel, as disclosed in Figs. 3 and 4. In this construction the four conical sections 38, 31, I8 and 39 may take the place of two or more oi the conical tubular sections oi Fig. 1. By this means several different grids, screens, cathodes or other electrodes may be mounted from conical assembly. The tab-like portions 40 could act as leads to each of these sections.

It is not necessary that all conical portions of this device be assembled, as shown in the first figure. Several conical sections might be superimposed one upon another in not as close a relation as disclosed in Fig. l but to operate further apart as disclosed in Fig. 5. Here we have a bottom portion 4| with its upper portion 42 in conical inward relationship with the outer conical flare 43 oi the next section 44. The vitreous material 45 seals these two adjacent conical sections 42 and 43. Likewise the section 44 has its upper conical portion 46 sealed to the lower portion 41 of the next metal section 48 by the vitreous seal 49 and the section 48, in turn, has its upper conical portion 50 sealed to the lower conical portion ii of the top section 52 by the vitreous seal 53.

Fig. 5 also discloses a preferred arrangement of the cathode 54 between the sections 41 and 44 and the section 48 supporting the grid 55. The upper portion 52 will act as an anode.

If desired, the glass may be extended over any part or the cylindrical section in addition to the conical part in which case it will serve to increase the electrical leakage, particularly between ad- Jacent metal members. For this purpose, it may also be extended over either the inner or outer surfaces or both, as desired.

In accordance with the patent statutes, we have described particular embodiments of our invention, but it will be recognized that these are intended to be illustrative only and that the broad principle thereof will be capable of alternative embodiments which will be evident to those skilled in the art. We desire, accordingly, that the claims shall be given the broadest construction of which their terms are susceptible in view oi the prior art.

We claim as our invention:

1. A casing for an electrical discharge device consisting of a plurality 01 metal conical members and insulation therebetween, electrodes within the casing, said metal members acting as the sole connections to said electrodes.

2. A casing for an electrical discharge device consisting of a plurality of superimposed metal conical members and insulation therebetween,

electrodes within the casing, said metal members acting as the sole connections to said electrodes.

3. A casing for an electrical discharge device consisting of a plurality of nested metal conical members and insulation therebetween, electrodes within the casing, said metal members acting as the sole connections to said electrodes.

4. A casing for an electrical discharge device consisting of a plurality of nested superimposed metal conical members and insulation therebetween, electrodes within the casing, said metal members acting as the sole connections to said electrodes.

5. An electrical discharge device comprising a plurality of conical sections, insulation between said sections, a cathode connected to two oi said sections, and another of said sections adapted to act as anode structure.

6. An electrical discharge device comprising a plurality of superimposed metallic sections, insulation between said sections, a cathode extending from one section to another section, a control electrode structure supported by another section and another section adapted to act as anode structure.

" DEWEY D. KNOWLES.

ERWIN F. LOWRY. 

